Updated December 16, 2022
Although one does not need to be an expert in sleep science to know what it is, the more technical side of sleep is fairly extensive. Sleep is a period of inactivity which results in decreased responsiveness to external stimuli. Scientists define sleep based on brain wave activity patterns and other physiological changes. Many physiological levels remain constant throughout the day at levels that are optimal for the body's functions but at night demand decreases and our temperature and blood pressure drop.
We know from extensive sleep science that not every physiological duty of the body decreases during sleep. For example, an increase in the release of growth hormones is induced by sleep. Certain physiological activities associated with digestion, cell repair, and growth are often at their peak during sleep, suggesting that cell repair and growth may be an important function of sleep. Although scientists remain unsure precisely why we sleep, there are many clues about the functions that sleep serves and how getting more and higher quality sleep can improve our health and well-being.
Transitions between wakefulness and sleep are controlled and regulated by the brain, which also plays a key role in directing the quantity and depth of sleep. However, sleep is also strongly influenced by external factors, such as light and caffeine. When the areas of the brain that promote sleep are most active, they inhibit activity in areas of the brain responsible for promoting wakefulness. This inhibition of wakefulness results in stable sleep and is a key component of sleep science.
Under normal conditions, two systems inside the body interact to allow us to sleep and remain alert when we want to: Our drive for sleep and our body's internal clock. Our internal clock, or circadian rhythm, uses light to determine the function of the body. It tells us when it's time to sleep and when it's time to awaken.
During non-rapid eye movement (Non-REM) sleep, we go through stages of light and deep sleep. During the first stage, we're easily awoken. Our eye movement is slow, and our muscles may be active. During the second stage, heavier sleep begins to set in. We become disengaged from our surroundings, our heartbeat and breathing become steady, our body temperature drops, and our brain waves slow down.
We sleep the deepest during the last two stages of Non-REM sleep. We're hard to awaken as the blood supply increases to our muscles. Our blood pressure drops and our breathing slows as our muscles relax. During these stages, our body creates new tissue, repairs cells, and releases growth hormones.
Although the average person is not fluent in all the specifics of sleep science, most have heard the term REM. During rapid eye movement (REM) sleep, our breathing becomes more rapid and irregular. Our heart rate and blood pressure increase, and our arms and legs become paralyzed. This is the stage of sleep where our most vivid dreams occur. We typically remember dreams best when we're awoken from REM sleep.
If you suffer from painful chronic ailments, such as backaches or headaches, then you might want to spend more time in bed. A study conducted at Henry Ford Hospital in Detroit finds that getting extra sleep every night could provide relief. Dr. Thomas Roth, senior scientist of the Sleep Disorders and Research Center at Henry Ford says:
"If you are already sleeping eight hours a night, you probably don't need more sleep. If you spend six hours in bed each night, spend eight - preferably nine."
Roth recruited 18 pain-free, healthy volunteers who were, over the course of four days, assigned to either maintain their regular sleep schedule (habitual group, or HAB)or extend their rest to ten hours (extension group, or EXT). Roth's team then tested pain sensitivity by asking subjects to hold a finger against a radiant heat source.
Subjects who increased their sleep could hold their fingers to the heat source 25% longer than those who maintained their regular sleep schedule. The average finger withdrawal latency increased (pain sensitivity was reduced) significantly in the EXT group from experiment day 1 to day 4*. The results for the EXT and HAB groups on experimental days one and four are shown in the chart below.
*97% statistical confidence; F=5.68, p<0.03
So how does sleep help to reduce pain? And how much is enough sleep? Read on to learn about the healing powers of sleep and how it can dramatically improve your overall well-being.
Although our busy lives may try to convince us that adequate sleep is a luxury, it's actually crucial to our health. This is in large part because sleep and pain have a codependent relationship, meaning each can have a direct impact on the other; too much pain can cause us to lose sleep, and not enough sleep can cause increased pain. Treat one, and quite often the other improves! In fact, one study found that face-to-face cognitive behavioral therapy to improve sleeping habits not only helped participants with insomnia, they also saw a mild to moderate decrease in pain immediately following therapy.
Let's look at this scientifically. While we sleep, our bodies take the opportunity to repair and renew at the cellular level - that's part of why it's so important to rest while you're sick, injured, or recovering from surgery. Without enough sleep, the body doesn't have enough time to properly repair and rejuvenate, which makes us more sensitive to pain. Tolerance decreases and the pain we feel is amplified.
And it isn't just about getting the right amount of sleep. Studies have found that disruptions in the REM cycle can cause fibromyalgia sufferers to experience heightened pain levels, while better quality rest can actually reduce discomfort. Similarly, an otherwise healthy person who experiences disruptions throughout the night may suffer pain sensitivity similar to fibromyalgia.
A common suggestion doctors have for chronic pain sufferers is to stay active and get regular exercise. Unfortunately, this can be difficult for someone experiencing so much discomfort that even walking is a challenge. On top of that, since pain can hinder adequate rest, patients often feel too exhausted to exercise. But like sleep and pain, sleep and exercise often affect each other - we tend to sleep better when we exercise and we're more likely to exercise if we're well-rested - and this can have a positive impact on chronic pain.
Simply put: better sleep not only lessens your discomfort but also makes you more likely to participate in other activities that will help lower your pain even more.
Just because you can get by on less sleep doesn't mean you should. So what's the right amount? According to experts, needs will vary depending on your age, health, and lifestyle, but in general, adults should get about eight hours every night to feel properly rested.
This recommended sleep times chart can help you figure out your general range based on your age, but you'll also need to consider any behaviors that affect the quality and quantity of the sleep you're getting. For example, if you're an adult working an average of 50 hours a week, it's possible you might need closer to nine or ten hours to fully recharge your brain and body.
Depending on your situation getting a full eight hours every night might seem like an impossible feat, but there are a few ways you can make sure you get enough sleep. Start by sticking to a regular sleep schedule, even on weekends: get to bed at about the same time every night and get up at the same time each morning. Don't just get in bed and hope your mind stops racing - create and stick to a nightly routine to help you relax and get your mind and body ready for rest. Check out our page on sleep essentials to learn how to set up a proper sleep environment.
Be sure your bedroom creates an environment conducive to sleep: a comfortable temperature, adequate darkness, and no disturbing sounds or electronics that could wake you. And of course, your mattress and pillows should be comfortable enough that you wake up feeling refreshed.
Even if you aren't suffering from chronic pain, there are endless benefits to getting enough rest on a regular basis. For starters, sleep is literally good for your brain!
Just as your body is at work repairing itself while you sleep, your brain is making important connections, as well. It consolidates the memories you created throughout the day, meaning that if you're learning a new skill or information, sleep can actually help commit the information and processes to memory. So those all-nighters you're pulling are actually working against you - you'll perform much better if you let your brain rest! For more information on this topic, readSleep On It - Why Sleep is Important for Optimizing Learning and Memory [PDF] by H. Craig Heller, PhD, and Elsa C. Pittaras, PhD from Stanford University.
Better sleep can also sharpen your attention span and focus, which means you can be more productive at work or school, be less likely to get into an accident while driving, and improve your relationships. It can dramatically improve your mood and lower feelings of depression and anxiety, which can have positive physical effects like lower blood pressure and even lower cholesterol. As a result, your risk for heart disease can decrease significantly.
There are physical benefits, too! Some studies suggest that more sleep can reduce your chances of developing diabetes and certain kinds of cancer. It can also lead to a healthier heart, more radiant skin, and even help you on your quest to a healthier weight by losing more excess body fat versus muscle mass.
So what are you waiting for? Make sleep a priority in your life and reap the physical and mental benefits.